Sear actuated electric firing device



June 5, 1951 BIRD 2,555,311

SEAR ACTUATED ELECTRIC FIRING DEVICE Filed Dec. 3, 1948 Patented June 5, 1951 UNITED STATES PATENT OFFICE SEAR AOTUATED ELECTRIC FIRING DEVICE John B. Bird, Belmont, Mass.

Application December 3, 1948, Serial No. 63,423

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 2 Claims.

The invention described in the specification and claims may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty there- OIL This invention relates to a sear mechanism for an electrical discharge device utilized for firing of rockets from a rocket launcher and similar devices.

It is an object of this invention to provide a scar mechanism for an electrical discharge device for rocket launchers.

A particular object ofthis invention is to provide a sear mechanism for disconnecting the trigger from an electrical discharge device whereby the trigger will return to its normal position without effecting another electrical pulse.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a longitudinal sectional view of the electrical discharge device shown secured to the underside of a rocket launcher barrel with the trigger in normal position.

Fig. 2 is a detail view similar to Fig. 1 showing the position of the trigger mechanism in the fully retracted .position of the trigg r.

Fig. 3 is a detail perspective view of the sear and related elements.

Fig. 4 is adetail view similar to Fig. 1 showing the armature about to be rocked, and the position of the trigger immediately before the sear is disengaged from the rocker arm upon rocking of the armature.

This invention essentially comprises a rod-like sear member having 2. lug portion thereon engageable with the rocker arm of an electrical firing device utilized for generating an electrical impulse for firing a rocket projectile from a rocket launcher. Such sear is pivotally secured to a trigger and is arranged to contact a screw having a conically shaped head whereby the sear is cammed out of engagement with the armature of the electrical discharge device after the electrical impulse has been generated, the sear acting to disconnect the trigger from the armature so that no impulse will be generated on the return of the trigger to the normal or firing position.

There is shown in assembled relation in Fig. 1 an electrical discharge device utilized with a 'yembodying the sear mechanism of this invention.

The electrical discharge device essentially consists of a frame Ill which includes spaced parallel bars H and I2 separated at each end by a magnet i3 and [4. Frame II] is mounted on the underside of a barrel 15 of a rocket launcher (not shown) and a depending lug I6 welded to the underside of barrel I5 is utilized for such purpose. Frame ill is secured to lug I6 by a clamp 11.

A field coil I8 is supported within frame [0 midway between magnets l3 and I4 and an armature i9 is mounted within coil [8 for movement throu h a limited arc therein. A pivoted rocker arm .26, pivoted in the frame 10 as at of ,substantially lJ-shape construction is connected at each end of armature 19 by a correspondingly shaped wire spring 2! pivotally attached to the rocker arm2l3 by means of a cotter pin 20".

go There is however an upwardly projecting arm 22 provided on rocker arm 20 and a scar notch 2 3 is provided in the extreme upper end of arm 22 for a purpose to later appear, A cover 24 normally surrounds frame [0 but is only shown broken away as illustrated in Fig. 1. Near the bottom or rocker arm 20 there is provided a spring '25 which acts against the cover 24 as well as against rocker arm 20 to bias armature 19 in the position shown in Fig. 1 and to normally retain such armature in such position.

A tri ger .26 is pivotally secured to the forward end of lug 16 by a transverse pin 21. Trigger 25 depends from lug Hi and substantially in the center of such dependin portion .Of the trigger there is provided a recess 28 for a purpose to shortly appear. A sear .29 is .slidably mounted in cover 24 for transverse movement with respect .to frame 10. Sear 29 comprises essentially a square rod-like portion ,3!) having a forwardly projecting end 3i of round configuration and of substantially smaller diameter than the width of the square portion of such sear. Rod 30 terminates in a cylindrical head 32 in which there is provided an axially disposed hole 33. The round portion 3| of scar 29 projects through a slot 43 provided in cover 24. The cylindrical head portion 32 reposes in recess 28 and a transverse pin 34 passes through trigger 26 and hole 33 on the head portion 32 whereby sear 29 is pivotally secured to trigger 26. A spring 35 surrounds end 3| and acts between head 32 and cover 24 to bias trigger 26 away from such cover. The shoulder formed at the junction of round and square portions of sear 29 bears against the inside of rocket launcher employed by the armed forces cover 23 on opposite sides of slot 43. Thus such shoulder acts as a stop whereby the clockwise movement of trigger 26 is limited.

Sear 29 is provided with a depending lug or hook 36 having a sloped surface 36 and a shoulder 31, Such shoulder is engageable with the sear notch 23 provided in the upstanding arm 22 of rocker arm 20. A sloped cam surface 38 is provided on the extreme rear end of rod-like portion 30 and is engageable with a cam 39. Such cam comprises a screw which is threadably secured to bar H of frame as shown in Fig. l and opposite to sear 29. The end 42 of cam 39 is conically shaped as shown in the drawings. A yoke-like spring 4|] is secured to the top of bar l2 of frame 19 as by a rivet 41. Spring 40 bears against the upper surface of the sear 29 as shown in Fig. 1 for maintaining sear 29 in engagement with the pivoted arm and subsequently with the cam 39 as shown in Figure 2.

When the trigger is pulled rearwardly shoulder 31 of the sear 29 being in engagement with the sear notch 23 of the rocker arm carries rocker arm 20 with the sear a distance to sufliciently stress the spring 2 I, as at 2i in Figure 4, causin said spring to snap the armature 19 to a position opposite its normal position whereupon sloped end 38 of sear 29 engages conical end 42 of the cam 39. Thus sear 29 is deflected upwardly whereby shoulder 31 is disengaged from spring which in turn causes the spring 2| to snap the armature back to its normal position shown in Figure 2 with the trigger still in pulled position. When the trigger is released the sear 29 is pulled forward by means of spring 35, the sloped surface 36 riding over the frame 22 adjacent the sear notch and the shoulder 31 subsequently engaging the sear notch. Thus it is obvious that electrical impulses are generated only when the trigger is pulled rearwardly and not upon release of the trigger. electrical impulse was generated when the trigger was pulled rearwardly and another electrical impulse was generated when the trigger was released thus involving the dangers of hangfire.

From the foregoing description it is clearly apparent to those skilled in the art that there is-here provided a simple yet positive sear mechanism for an electrical firing device utilized with rocket launchers and the like for discharging the rocket fixed therefrom.

I claim:

1. In an electrical firing device for a rocket launcher having a frame, a coil mounted on the Formerly an 2 frame, an armature mounted within the coil and movable through a limited arc, a spring normally maintaining the armature in one position, and a rocker arm connected to the armature, the improvement comprising a trigger pivotally mounted on the frame, a sear pivotally secured on one end to said trigger, said searbeing provided with a rod-like member with a sloped cam surface on the free end thereof and having a downwardly disposed hook portion intermediate the ends engageable with the rocker arm in the normal position of the armature, cam means engageable by said cam surface of said sear in the pulled position of said trigger whereby said sear is disengaged from the rocker arm, resilient means maintaining said sear against said cam means, and spring means surrounding said sear urging said sear and said trigger to the unpulled position. I

2. In an electrical firing device for a rocket launcher having a frame, a coil mounted on the frame, an armature mounted within the coil and movable through a limited are, a spring normally maintaining the armature in one position, and

a rocker arm connected to the armature, the improvement comprising a trigger pivotally mounted on the frame, a sear pivotally secured on one end to said trigger, said sear being provided with a rod-like member with a sloped cam surface on the free end thereof and having a downwardly disposed hook portion intermediate the ends engageable with the rocker arm in the normal position of the armature, a screw secured in the frame and opposed to said sear, said screw having a conical end portion adjacent said cam surface of said sear whereby said sear is cammed out of engagement from the rocker arm in the pulled position of said trigger, re-

said sear against said conical end of said screw, and spring means surrounding said sear urging said sear and said trigger to the unpulled position.

JOHN R. BIRD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 992,854 Cobb May 25, 1911 1,387,369 Duffek Aug. 9, 1921 1,637,079 Karner July 26, 1927 2,185,460 Harris Jan. 2, 1940 2,376,557 Severance May 22, 1945 2,465,402 Skinner et al Mar. 29, 1949 

